Absorbent body which includes cavities

ABSTRACT

An absorbent article which includes a liquid-permeable outer sheet (1) mounted on a first surface of the article, a liquid-impermeable outer sheet (2) mounted on a second surface of the article, and an absorbent body (3) which is enclosed between the two casing sheets and which includes a receiving space (24) for receiving and accommodating body liquid or fluid, the space comprising at least one cavity or region of lower density than the density of a part of the absorbent body (3) located adjacent the receiving space (24) generally in the same plane. The article is characterized in that the receiving space (24) is disposed in a storage layer (19) in the absorbent body (3), wherein the storage layer (19) is formed from a web of material which is divided in the longitudinal direction of the web along a dividing curve (20) which is undulating along at least part of its length so as to cross a line (21) extending in the longitudinal direction of the web at least two times, and the web-parts (22, 23) are displaced relative to one another in the plane of the web such that the web-parts (22, 23) will define the receiving space (24) therebetween in the plane of the web.

The present invention relates to an absorbent article which includes aliquid-permeable outer sheet disposed on a first article surface, aliquid-impermeable outer sheet disposed on a second article surface, andan absorbent body which is enclosed between the two outer sheets andwhich includes a receiving space in which body liquid is taken up, saidspace consisting in at least one cavity in the absorbent body.

Hitherto, the problem encountered with absorbent articles, such asdiapers, incontinence guards, sanitary napkins or like articles whichare intended to repeatedly receive and absorb body liquid, or fluid,discharged by a user is that the rate at which the liquid is able topenetrate into the article decreases considerably with each new wettingoccasion. This problem is particularly pronounced in diapers andincontinence guards that are intended for children and adults, since inthese cases the quantities of liquid that the article will receive andabsorb are relatively large and are discharged within the space of onlya few seconds. It is therefore not unusual, particularly after a firstwetting of the article, that the liquid which is not able to penetrateinto the article immediately will instead flow over the surface of thearticle and leak past the edges thereof. Such leakage of body liquid isnaturally highly undesirable, since it is liable to soil the clothes,bed linens and mattresses used by the wearer, and even stain and destroysuch commodities.

The reason why the body liquid penetration rate decreases with repeatedwetting of the article is because the absorbent body of the articlebecomes saturated with body liquid temporarily within a limited areaaround the area on the article surface in which the body liquid firstimpinges, the so-called primary wetting area. The absorbent articles arenormally comprised of one or more layers of hydrophilic fibres, forinstance cellulose fluff pulp, and often also include a powerfulabsorbing hydrocolloidal material, so-called superabsorbents. Liquid istransported relatively slowly through such materials, sincetransportation of the liquid is mainly governed by the capillary forcesacting in the cavities located between fibres and particles in theabsorbent body of the article. Liquid is transported within thehydrocolloidal materials by diffusion, which is a still slower processthan the process generated by the capillary forces. The liquid willtherefore remain in the primary wetting area of the article for arelatively long period of time and will then gradually be transportedout to surrounding parts of the absorbent body.

It is known to provide the article with liquid-transporting means in theform of compressed patterns, for instance compressed stripes, whichfunction to disperse the liquid in the longitudinal direction of thearticle, so as to steer the transportation of liquid away from theprimary wetting area to parts of the absorbent body in which absorbentmaterial is still unused. An article possessing such compressed stripesis earlier known from PCT/SE94/00835. Liquid transportation in thearticle is mainly the result of the differences in capillary forcesacting between the compressed stripes and surrounding material. Eventhough a positive effect is obtained in this case in the form of adirected liquid flow in the absorbent body, the rate at which liquid istransported in the article is much too slow in relation to the rate atwhich body liquid is discharged to the article. Consequently, there is arisk that liquid will not be absorbed quickly enough, but instead willrun along the surface of the article and out over the edges thereof,resulting in leakage, this risk being particularly manifest in productswhich are intended for urine absorption, such as diapers andincontinence guards, onto which large quantities of liquid are oftendischarged over a short period of time. Furthermore, heavy compressionof the article results in rigid parts which do not flex easily and whichprevent the article from following satisfactorily the movements of thewearer's body and conforming to the shape of the wearer's body in use.

Another method of obtaining an effective and instant ability to receiveand retain large volumes of body liquid is to create different types ofliquid-receiving cavities, or basins, in the article.

U.S. Pat. No. 3,889,679 describes a diaper in which a plurality ofcircular holes extend through the absorbent body of the diaper. Theseholes are intended to receive and accommodate liquid discharged to thediaper over a short period of time. The absorbent material surroundingthe holes then absorbs the liquid by suction. Such liquid receivingholes fulfil their function relatively well, at least upon initialwetting of the diaper. The manufacture of a cavitated absorbent body,however, is a relatively complicated procedure.

Swedish Patent Application No. 9304321-4 describes an absorbent body forabsorbent articles such as diapers, incontinence guards and sanitarynapkins, which is provided with a liquid-receiving part in the form of awell which is located generally opposite the anticipated primary wettingarea of the absorbent body and which extends depth-wise into and througha liquid storage part in the absorbent body. The well is in liquidcommunication with a liquid-dispersion layer disposed beneath a liquidstorage layer and has a larger effective mean pore size than thesurrounding liquid storage part.

An absorbent body of this kind also fulfils the function of receivingand accommodating a large quantity of body liquid, or fluid, dischargedabruptly to the diaper. The manufacturing process of the absorbent body,however, is complicated, particularly in the case of high productionrates.

The object of the present invention is therefore to provide a simple andinexpensive method of producing liquid-receiving cavities, channels orlike configurations in an absorbent layer or sheet, essentially withoutwasting material.

This object is achieved in accordance with the invention with the aid ofa method which is characterized by forming the receiving space in astorage layer in the absorbent body, wherein the storage layer is formedfrom a web of material which is divided in the longitudinal direction ofthe web along a dividing curve which undulates along at least a part ofits length such as to cross at least twice a line extending in thelongitudinal direction of the web; and by displacing the web-parts inrelation to one another in the plane of the web such that the web-partswill define the receiving space therebetween in the plane of the web.

According to one embodiment of the invention, the web-parts aredisplaced relative to one another in the longitudinal direction of thedividing or separating curve, such that the web-parts will define atleast one cavity therebetween.

According to another embodiment, the web-parts are displaced in adirection away from one another in the transverse direction of the web,whereby the storage layer exhibits a channel-like undulating spaceextending between the web-parts.

The web-parts may be placed in the article with the undulating curveextending either in the longitudinal or in the transverse direction ofthe article.

By undulating curve is meant any desired curve form, such as asinusoidal curve, sawtooth curve, square-wave curve, etc. The waves orundulations may extend along a straight, curved or wavy line.

According to a further embodiment of the invention, the web-parts aredisplaced mutually in the longitudinal direction of the web such thatthe dividing curve maxima on respective sides of the line extendinglongitudinally in the web will be located essentially opposite oneanother, and such that a line extending generally perpendicular to theline extending longitudinally through the web can be drawn through themaxima of said dividing curve, whereby the web-parts define therebetweena row of holes alternating with intermediate overlapping web-parts inthe longitudinal direction of the web.

The size of the holes can be varied by varying the amplitude of thewaves or undulations, for instance so that the holes in the wetting areawill be larger than the holes outside the wetting area.

In the case of a particularly preferred embodiment, those parts of thestorage layer that lie adjacent the storage space include a materialwhich increases in volume in a direction generally perpendicular to thefirst surface of the article when wetted, whereby the size of thestorage space also increases in said direction as a result of wetting ofthe article.

A suitable material in this regard is formed from a particle materialwhich includes flash-dried cellulose fibres that have been dry-formed toprovide a web having a surface weight of 30-2000 g/m² and compressed toa density of between 0.2-1.2 g/cm³, said web being incorporated in thearticle without subsequent defibration and fluff formation.

Another suitable material is formed from an air-laid web of cellulosefibres which is compressed to a dry-form sheet having a first density ofbetween 0.2-1.2 g/cm³, whereafter the sheet is softened mechanically toa second density which is lower than the original density and therewithdelaminated so as to form a plurality of incompletely separated thinfibre layers whose density corresponds to the first density.

Other examples of suitable storage layer materials are an air-laid webof cellulose fluff pulp which has been compressed to a density of atleast 0.1 g/cm³ preferably at least 0.12 g/cm³, and an air-laid web ofcellulose fluff pulp having mixed therein a given proportion ofthermoplastic fibres, whereafter the fibre web has been thermobonded.The air-laid web of cellulose fluff pulp may also include a givenproportion of superabsorbent. Wet-laid fibre structures may also be usedin accordance with the invention.

Another suitable storage layer is formed from a web of material having afirst thickness and including resilient material, wherein the web iscompressed at right angles to a plane through the web to a secondthickness and is bonded in its compressed state with the aid of a binderthat will dissolve in body liquid, wherein bonding of the web ceaseswhen the web is wetted and the storage layer returns at least partiallyto the first thickness.

Alternatively, the storage layer may be comprised of a compressed foammaterial which will expand in its thickness direction when wetted, or ofa compressed fibre layer which comprises at least partially fibres whichhave a given resiliency in a wet state.

The receiving space in the storage layer may either comprise one or moreholes which extend through the thickness of the storage layer or atleast one channel-like cavity which extends in the longitudinaldirection of the article.

According to one embodiment, the proportion of storage layer volume thatis comprised of the receiving space is largest within the primarywetting area of the article, i.e. that area of the article which isintended to be first wetted by body liquid. The proportion of thestorage layer taken-up by the receiving space decreases, suitably in adirection away from the primary wetting area.

Holes and channel-like cavities can be formed readily in a layer ofmaterial without incurring wastage, by dividing the web along anundulating curve and then displacing the thus separated web-parts inrelation to one another. When the web-parts are displaced so as to forma row of openings which alternate with parts where the web-parts overlapone another, the overlapping parts of material can provide furtheradvantages. For instance, this enables the absorption capacity of anabsorbent article which includes an absorbent layer formed from such aweb of material to be increased, since the overlapping parts therewithhave twice the absorption capacity of the remainder of the absorbentlayer. The absorbent layer is advantageously arranged so that theoverlapping parts will be located where a higher absorption capacity ismost desirable. In the case of a diaper, sanitary napkin or likearticle, it may be suitable for the overlapping parts to be located inthe crotch part of the article, i.e. the part of the article which liesin the crotch region of the wearer in use. The crotch part is that partof the article in which essentially all liquid is absorbed primarily.

However, it is suitable to provide within that region of the crotch partwhich is expected to be wetted by discharged body liquid first, i.e. theprimary wetting area, liquid-receiving cavities in which the liquid canbe accommodated prior to being absorbed by the surrounding absorbentmaterial.

Another advantage afforded by the overlapping parts is that when theseparts are formed from a material which expands in the thicknessdirection when wetted, said parts will function as spacing means betweenthe wet absorbent body and the wearer.

The method applied in dividing the web is not significant to theinvention. Any conventional cutting or clipping method can be used. Forinstance, the web can be divided by cutting the web apart with the aidof a knife roll, by cutting with the aid of ultrasonic cutters, highpressure water jets, lasers, or like devices.

A number of different cutting curves and variants in displacingdifferent web-parts in relation to one another are conceivable withinthe scope of the invention. For instance, the undulating cutting curvesneed not have the same amplitude along the whole of their lengths, andthe curve may have two or several maximal amplitudes. All types ofcutting curves which cross a line extending longitudinally in the web atan appropriate frequency can be used, provided that they will result inat least two web-parts which extend in the longitudinal direction of theweb and which can be displaced mutually such as to define together anintermediate cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings.

FIG. 1 illustrates from above a diaper constructed in accordance with afirst embodiment of the invention.

FIG. 2a is a longitudinal sectioned view of the diaper shown in FIG. 1,taken on the line II--II prior to wetting the diaper.

FIG. 2b is a longitudinal sectioned view of the diaper shown in FIG. 1,taken on the line II--II after wetting the diaper.

FIGS. 3-7 illustrate different embodiments of webs provided withcavities in accordance with the invention, said webs being shown in aflat state.

DESCRIPTION OF EMBODIMENTS

The diaper illustrated in FIGS. 1, 2a and 2b is seen from the side whichlies proximal to the wearer in use. The diaper is shown extended in aflat state and includes a liquid-permeable first casing sheet 1, madefor instance of nonwoven material, woven material, perforated plasticfilm or net mounted on that side of the diaper which is intended to lieproximal to the wearer in use. A liquid-impermeable second casing sheet2 made, for instance, of plastic film or a nonwoven material or wovenmaterial that has been made hydrophobic, is mounted on that side of thediaper which is intended to lie distal from the wearer in use. The twocasing sheets 1, 2 embrace an absorbent body 3 and are mutually joinedtogether within parts 4 of the casing sheets 1, 2 that project outaround the absorbent body 3.

The diaper is constructed so that it will embrace the lower part of thewearer's torso in a pants-like fashion when in use. To this end, thediaper has a front part 5 which, in use, is intended to face forwardlyof the wearer and lie over the wearer's stomach, a rear part 6 which, inuse, is intended to face rearwardly of the wearer and lie in abutmentwith the wearer's buttocks, and a crotch part 7 disposed between thefront part 5 and the rear part 6 of the diaper and intended, in use, tobe located in the crotch area between the wearer's thighs. The diaperhas a generally hourglass shape, wherein its front part 5 and rear part6 are broader than the crotch part 7. The diaper also includes twolongitudinally extending side-edges 8, 9 and a front waist edge 10 and arear waist edge 11. When the diaper is worn, the longitudinallyextending side-edges 8, 9 form the edges or borders of the leg openingsof the diaper, whereas the waist edges 10, 11 together embrace the waistof the user and form the waist edge or border of the diaper.

An elastic device 12, 13 is mounted along each respective side-edges 8,9 of the diaper. The elastic devices 12, 13 are mounted on the diaper ina stretched state and when contracting gather in the side-edges 8, 9 ofthe diaper and curve the diaper into a trough-like shape. The effect ofthe elastic devices 12, 13 is not apparent from FIG. 1, however, sincethe diaper is shown in a flat state with the elastic devices 12, 13 in astretched state. In use, the elastic devices 12, 13 function to hold theedges of the diaper leg openings in sealing abutment with the wearer'sthighs. A further elastic device 14 is mounted along the rear waist edge11 of the diaper, so as to obtain sealing abutment with the edge of thewaist opening in a corresponding manner. Several different types ofelastic devices 12-14 suitable for this purpose are known to the art,such as elastic threads, elastic bands, elastic nonwoven, or likematerials.

In order to enable the diaper to be secured in use in a pants-like formaround the wearer's body, a fastener tab 15, 16 is provided on arespective side-edge 8, 9 in the proximity of the rear waist edge 11.The fastener tabs 15, 16 are intended to coact with and fasten against afastener receiving region 17 provided on the front diaper part 5. Thefastener tabs 15, 16 are normally in the form of self-adhesive tapeswhich prior to use are folded over with the adhesive-coated surfacelying against and protected by a fastener tab area that has been treatedwith a release agent, or on the diaper itself. The receiving region 17is comprised of a reinforced region of the liquid-impermeable casingsheet 2 on the front part 5 of the diaper. This reinforcement issimplest achieved by laminating a plastic film strip on that side of theliquid-impermeable casing sheet 2 that lies distal from the absorbentbody 3. This reinforcement of the receiving region 17 enables the diaperto be opened and refastened without tearing the liquid-impermeablecasing sheet 2.

Alternatively, the fastener tabs 15, 16 may comprise any appropriatetype of mechanical fastener means, such as one part of a Velcro® tapefastener, a press stud or equivalent means. In this regard, thereceiving region 17 will be comprised of the corresponding part of themechanical fastener device. It is also known to use fastener means whichcan be considered essentially as hybrids between adhesive fastenerdevices and mechanical fasteners. An example in this regard is describedin EP-A-393,953. No fastener devices are required in the case of diaperswhich are intended to be supported as inserts in a pair of tightlyfitting pants. So-called pants-type diapers, or trainers, also normallylack fastener devices.

The absorbent body 3 includes a first absorption layer, the liquid orfluid-receiving layer 18, which has essentially the same shape and sizeas the diaper itself and which is located nearest inwardly of theliquid-permeable casing sheet 1. The liquid-receiving layer 18 issuitably comprised of a soft material of high liquid-permeability andhaving relatively large pores or capillaries. An example of suchmaterial is lightly compressed cellulose fluff layers, in particularlycomprised of mechanical, thermomechanical or chemithermomechanical(CTMP) pulp, or fibre mats and wadding of other kinds comprised ofnatural fibres or of synthetic fibres. Mixtures of cellulose fluff pulp,or other cellulose based fibres, with different types of syntheticfibres may also be used. It is also possible to use soft perforated oropen-cell foam material. Such material has a low liquid dispersioncapacity, whereby the wet area of the layer will remain restrictedessentially to the primary wetting region even after repeated wetting ofthe layer or sheet. The wearer thus feels the surface of the diaper incontact with the wearer to be dry and comfortable against the skin, evenafter having worn the diaper for a relatively long time.

When the diaper is in use, the receiving layer 18 is intended to receivedischarged body liquid and to transport the liquid away from theliquid-permeable casing sheet 1 and will therefore have large poreswhich offer as little resistance as possible to the liquid flow. Thereceiving layer 18 will preferably also be soft and feel comfortableagainst the wearer's skin during the full period of its use. Theproperties of the material in the receiving layer 18 will preferably nottherefore change essentially after being wetted. It is also desirablefor the material to have a given resiliency, so that it will endeavourto return to its original state after being compressed or wrinkled,pleated, in use.

When the receiving layer 18 includes cellulose fibres which normallyhave a relatively low resiliency in a wet state, for instance chemicalpulp, it may be suitable to admix the cellulose fibres with anothermaterial which will enhance the wet resilience of the material andtherewith impart to the first absorption layer a given degree ofresilience even in a wet state. Examples of such materials includedifferent types of thermoplastic fibres or particles which, when thelayer is heated, will function to bind the fibres in the layer andtherewith fixate the fibres in their mutual positions and therewithimpart to the layer a higher tensile strength and improved resiliency inboth a wet and a dry state. Cellulose fibres can also be modifiedchemically, e.g. by cross-linking, such as to enhance their inherentresiliency, or the cellulose fibres can be mixed with highly resilientsynthetic fibres.

The receiving layer 18 may also include a minor quantity of so-calledsuperabsorbents, i.e. material in the form of fibres, particles,granules, film or the like which is able to absorb and bind body liquidin an amount corresponding to several times the intrinsic weight of thesuperabsorbents while chemically forming an hydraulic gel.

Seen in a direction from the liquid-permeable casing sheet 1, there isdisposed inwardly of the receiving layer 18 a second absorbent layer 19which is intended to be able to receive and collect relatively largequantities of body liquid in a short period of time. The secondabsorbent layer, the storage layer 19, is formed from a web of materialwhich has been cut in two longitudinally along a sinusoidal curve 20which extends along the longitudinally extending centre line 21 of theweb, wherein the sinusoidal curve swings or undulates forwards andbackwards over the centre line 21. The two web-parts 22, 23 havethereafter been displaced in relation to one another through one halfwavelength in the longitudinal direction of the web. This results in theformation of a row of round holes 24 along the web centre line, theseholes alternating with intermediate overlapping web-parts 25. The holes24 constitute a cavity or region of a lower density than the adjacentparts of the web-parts 22,23. One flat surface of the storage layer 19is arranged in abutment with the receiving layer 18 and the other flatsurface is arranged in abutment with a third absorbent layer 26 locatedinwardly of the storage layer 19 nearest the liquid-impermeable casingsheet 2.

The diaper illustrated in FIG. 1 has its main extension in the XY plane,the X direction being defined by the transverse direction of the diaperand the Y direction being defined by the longitudinal direction of thediaper. The storage layer 19 is comprised advantageously of a materialwhich when wetted with body liquid will expand strongly in the Zdirection, i.e. in a direction perpendicular to the XY plane. Themanufacture of a particularly suitable material of this kind isdescribed in WO 94/10956. One characteristic feature of this material isthat it is produced by dry-forming flash dried cellulose fibres toproduce a web having a surface weight of 30-2000 g/m², which iscompressed to a density of between 0.2-1 g/cm³, and that the web isincorporated as an absorbent structure in an absorbent article withoutsubsequent defibration and fluff formation.

Another suitable expanded material is cellulose fluff pulp which hasadmixed therewith a given quantity of superabsorbent material,preferably at least 10 percent by weight superabsorbent material. Theaforedescribed materials are often produced in the form of relativelythin webs, having a thickness of only a few millimeters. The storagelayer can therewith be formed from one or more layers of such material.

Other appropriate storage layer materials are compressed foam materialor fibre wadding which when wetted will at least partially return totheir non-compressed size. When necessary, the materials may be fixatedin their compressed states with the aid of some form of water-solublebinder.

If considered suitable, the storage layer 19 may, of course, be producedfrom a web of material formed conventionally by air-laying cellulosefluff pulp, with or without the admixture of different types of bindingfibres or other additives. Different kinds of nonwoven material, tissuelayers or other wet-laid fibre structures may also be used. Theinvention may be applied to all web-like materials used in themanufacture of sanitary absorbent articles.

The third absorbent layer 26, hereinafter referred to as theliquid-dispersion layer 26, is comprised of a material of high densityhaving a high liquid-dispersing and liquid-retaining capacity. As withthe storage layer 19, the material described in WO/9410956 isparticularly usable in this regard. However, conventional compressedlayers of cellulose fluff pulp, absorbent foam material, or differentkinds of tissue laminates may be used. The liquid-dispersion layer 26 isgenerally rectangular in shape and has a smaller extension in the XYplane of the diaper than the receiving layer 18. The liquid-dispersionlayer will therefore be surrounded on all sides by a soft, body-friendlymaterial of low liquid dispersion ability. This arrangement affordsseveral advantages. Firstly, no sharp or hard edges on theliquid-dispersion layer 26 are able to come into contact with thewearer's body and chafe or irritate the wearer's skin; and, secondly,any movement of liquid conducted towards the diaper edges in theliquid-dispersion layer 26 is counteracted, therewith considerablyreducing the danger of body liquid leaking from the diaper. The edges ofthe liquid-dispersion layer 26 also form fold indications or directivesaround which the diaper is able to fold when compressed in the crotchregion between the wearer's thighs in use. In this way, the diaper willtake a size and shape which is better adapted to the space in the crotchregion.

The liquid-dispersion layer 26 is primarily intended to transport bodyliquid away from that region of the diaper on which the body liquid isfirst received, i.e. the primary wetting area. The absorbent material inthe absorbent body 3 is utilized more effectively in this way. This isachieved by compressing the liquid-dispersion layer 26 relativelyheavily, wherewith the layer obtains a high affinity to body liquid anda high liquid dispersion capacity. For the purpose of guiding liquidtransportation in the longitudinal direction of the diaper, theliquid-dispersion layer 26 may conveniently be provided with alongitudinally extending compression profile or pattern, in the form ofgrooves, wave patterns, or like configurations. The liquid-dispersionlayer 26 may also include a minor quantity of superabsorbent.

The two storage layer parts 22, 23 are suitably fastened to theliquid-dispersion layer 26, for instance glued thereto, so as to avoidsaid parts moving within the diaper. Alternatively, the storage layer 19may be fastened to a separate layer, for instance a layer of tissue ornonwoven, or may be fastened to the receiving layer 18. The storagelayer 19 may, of course, be fastened to more than one layer.

As shown in FIG. 2a, the storage layer 19 will have a relatively smallthickness prior to the diaper absorbing body liquid. The cavity 24formed between the two parts of the storage layer 19, however, issufficient to accommodate the amount of liquid first discharged. Theliquid discharged to the diaper will impinge on the liquid-permeablecasing sheet 1 thereof within a small limited area, the so-calledprimary wetting area, and pass quickly down through the casing sheet 1and the receiving layer 18. The liquid is collected in the holes 24between the overlapping parts 25 of the storage layer 19, and in thefibre structure proximal to the primary wetting area of the diaper. Theliquid is then spread gradually out in the XY plane of the diaper by theabsorbent material in the liquid-dispersion layer 26. This absorptionprocess is relatively slow, since it depends on the capillary forcesacting between fibres and particles in the absorption material. Thefibre structure nearest the wetting area will, in general, not have hadtime to be emptied of liquid before liquid is again discharged to thediaper.

However, a part of the liquid collected in the holes 24 in the storagelayer 19 on the first wetting occasion will be absorbed by the materialin said layer. Since this material is preferably of a kind which willexpand in the Z direction of the diaper when wetted, the receiving layer18 and the dispersion liquid layer 23 will move apart in the Zdirection, thereby enlarging the cavity 24 between the two absorptionlayers 18, 26. Consequently, when the diaper is next wetted the spaceavailable for instantaneous take-up of liquid will be equally as largeor larger than the space that was available on the first wettingoccasion. Thus, the rate at which liquid penetrates into the diaper willnot decrease to any appreciable extent, but in particularly favourableinstances may even increase with repeated wetting of the diaperabsorbent body 3.

The parts 25 lying between the holes 24 along the longitudinal centreline 21 of the storage layer 19 are comprised of two layers ofoverlapping web material. Since the web is relatively thin when dry, thedifference in thickness between the different parts of the storage layer19 are hardly noticeable when the diaper is dry. When wet, however, theoverlapping parts 25 swell twice as much as remaining parts of thestorage layer 19. This results in the formation of raised or elevatedparts 27 along the centre line 21 of the storage layer 19 which furtherincrease the distance between the receiving layer 18 and theliquid-dispersion layer 26 and between the receiving layer 18 and thoseparts of the storage layer 19 which consist of a single layer ofmaterial. This additional cavity 28 serves to make the diaper airy andcomfortable to wear in use. The overlapping parts 25 of the storagelayer 19 also impart an additional absorption capacity to the diaperalong the centre line 21, this additional capacity improving security ofthe diaper against leakage, particularly in the crotch part 7.

FIG. 3 illustrates a web of material in which holes 24 have been formedby first cutting the web 30 along a curved cutting line, and thendisplacing the thus separated web-parts 22, 23 longitudinally so as toobtain a repeating pattern of openings 24 and overlapping parts 25 inthe web 30. The web 30 shown in FIG. 3 has been cut longitudinally alongtwo essentially sinusoidal curves 20. As a result, two longitudinallyextending rows of holes 24 with intermediate overlapping parts ofmaterial 25 are formed when the edge-parts 22, 23 of the web aredisplaced in relation to the centre part 29 of the web. Of course, theprinciple can be applied to produce any desired number of rows ofopenings in a web. The number of rows of holes is determined in thisregard by the number of curved cuts made in the web.

The web 30 shown in FIG. 4 has been cut longitudinally along asinusoidal dividing curve 20, in the same way as the web 30 shown inFIG. 3. One edge-part 22 of the web 30 has then been displaced bothlongitudinally and transversely, way from the longitudinal centre line21 of the web 30. The other edge-part 23 has been displaced bothlongitudinally and transversely in towards the longitudinal centre line21 of the web 30. This enables the size of the holes 24', 24" and thesize of the overlapping parts 25', 25.increment. to be regulated oradjusted. When an edge-part 23 is displaced towards the longitudinalcentre line 21 of the web 30, the size of the holes 24" is decreasedwhile obtaining at the same time a larger overlap 25" between theweb-parts lying between the holes 24". Correspondingly, the size of theholes 24' is increased, by displacing the edge-part 22 of the web 30away from the centre line 21.

FIG. 5 illustrates how continuous, longitudinally extending openings 24can be obtained between parts of a web 30 that have been cut alongessentially sinusoidal curves 20. The web-parts 22, 23, 29 in FIG. 5 aredisplaced mutually both in the longitudinal and transversal direction ofthe web 30, by moving the cut edge-parts 22, 23 laterally in a directionaway from the longitudinal centre line 21 of the web 30. The width ofthe continuous channel-like opening 24', 24" between two web-parts isdetermined by the distance to which the web-parts are moved apart. FIG.5 shows two examples of openings 24', 24" of different widths.Naturally, the web 30 may include any desired number of continuousopenings of the kind described here.

FIG. 6 illustrates a web which has been cut along a sinusoidal curve anddisplaced through one-half wavelength in its longitudinal direction, soas to form oval holes 24.

FIGS. 7a and 7b illustrate a web of material 30 which has been cut in astraight line along certain parts of the web and which has been cutalong a sinusoidal curve 20 of varying amplitude along other parts ofthe web. When the web-parts 22, 23 are displaced through one-halfwavelength in the longitudinal direction of the web, holes 24 of varyingsizes re formed in certain parts of the web 30. The web is clipped orcut appropriately transversely to the straight cut parts and the clippedparts are incorporated in the absorbent body of an absorbent articlewith the largest hole located in the contemplated wetting area of saidarticle.

The web-parts can be placed in the article with the dividing curveslocated either in the longitudinal or in the transverse direction of thearticle. Other curve forms of any desired type can be chosen instead ofsinusoidal curves, for instance curves of a sawtooth or square-waveshape. As described above, the amplitude of the waves or undulations mayvary. The waves or undulations may also have a varying wavelength, inwhich case a varying overlap is obtained between the holes whendisplacing the web-parts to a given extent.

Although the invention has been described in the aforegoing mainly withreference to diapers, it will be understood that the invention can beapplied to all types of absorbent articles intended for the absorptionof body liquid or fluid. Examples of such articles are diapers andincontinence guards for children and adults, and also sanitary napkins,panty guards, bed protectors, seat protectors, dressings or likearticles.

I claim:
 1. An absorbent article, comprising:a liquid-permeable outersheet, a liquid-permeable outer sheet, and an absorbent body which isenclosed between the two outer sheets and which includes a receivingspace for receiving and accommodating body liquid or fluid, said spacecomprising at least one cavity or region of lower density than a densityof a part of the absorbent body located adjacent the receiving spacegenerally in the same plane, the receiving space is disposed in astorage layer in the absorbent body, wherein the storage layer is formedfrom a web of material which is divided in a longitudinal direction ofthe web along a dividing curve which undulates along at least part ofits length so as to cross a line extending in the longitudinal directionof the web at least two times to create web-parts; and the web-parts aredisplaced relative to one another in the plane of the web such that theweb-parts will delimit the receiving space therebetween in the plane ofthe web.
 2. An article according to claim 1, wherein the web-parts aredisplaced relative to one another in the longitudinal direction of thedividing curve such that the web-parts delimit at least one cavitytherebetween.
 3. An article according to claim 1 wherein the web-partsare displaced in a direction away from one another, in the transversedirection of the web, whereby the storage layer presents a channel-likeundulating space which extends between the web-parts.
 4. An articleaccording to claim 1, wherein the web-parts are placed in the articlewith an undulating curve extending either in the longitudinal or in thetransversal direction of the article.
 5. An article according to claim1, wherein the dividing curve is generally sinusoidal in shape.
 6. Anarticle according to claim 5, wherein the web-parts are displacedmutually in the longitudinal direction of the dividing curve such thatthe maxima of the dividing curve on both sides of the longitudinal linein the web will be located generally opposite one another, and so that aline extending generally perpendicular to the longitudinal line throughthe web can be drawn through the maxima of said dividing curve, wherebythe web-parts define therebetween a row of generally circular or ovalholes alternating with overlapping web-parts in the longitudinaldirection of the web.
 7. An article according to claim 1, wherein theundulations of the undulating curve vary in amplitude such that thereceiving spaces defined between the web parts will have varying sizes.8. An article according to claim 1, wherein portions of the web-partsthat lie adjacent the receiving space include a material which whenwetted will increase in volume in a direction generally perpendicular toa surface of the article, whereby the size of the receiving space willalso increase perpendicular to the surface as a result of wetting of thearticle.
 9. An article according to claim 1, wherein the liquidaccommodating receiving space is comprised of one or more holes whichextend through the thickness of the storage layer.
 10. An articleaccording to claim 1, wherein the receiving space is comprised of atleast one channel-like cavity extending in the longitudinal direction ofthe article.
 11. An article according to claim 1, wherein the storagelayer is formed from particle material which includes flash-driedcellulose fibres which have been dry-formed to provide a web having asurface weight of 30-2000 g/m² and compressed to a density between0.2-1.2 g/cm³ ; and in that the web has been incorporated in the articlewithout subsequent defibration and fluff formation.
 12. An articleaccording to claim 1, wherein the storage layer is formed from anair-laid web of cellulose fibres which has been compressed to adry-formed sheet having a first density of between 0.2-1.2 g/cm³,whereafter the sheet has been softened mechanically to a second densitylower than the original density and therewith delaminated, so as to forma plurality of incompletely separated thin fibre layers which have adensity corresponding to the first density.
 13. An article according toclaim 1, wherein the storage layer is formed from an air-laid web ofcellulose fibres which has been compressed to a density of at least 0.1g/cm³, preferably at least 0.12 g/cm3.
 14. An article according to claim1, wherein the storage layer is formed from an air-laid web of cellulosefibres in which there is admixed a given proportion of thermoplasticfibres and the fibre web has been thermobonded.
 15. An article accordingto claim 13, wherein the storage layer also includes a given proportionof superabsorbent material.
 16. An article according to claim 1, whereinthe storage layer is formed from a web of material having a firstthickness and including resilient material, said web having beencompressed perpendicular to a plane through the web to a secondthickness and bound in its compressed state with a binder which willdissolve in body liquid or fluid, wherein bonding of the web ceases whenthe web is wetted and the web returns at least partially to its firstthickness.
 17. An article according to claim 16, wherein the storagelayer is formed from a compressed foam material which expands in itsthickness direction when wetted.
 18. An article according to claim 16,wherein the storage layer is formed from a compressed fibre web which iscomprised at least partially of fibres that have a given resiliency in awet state.
 19. An article according to claim 1 wherein the storage layervolume taken up by the receiving space is greatest within an area of thearticle which is intended to be wetted first by body liquid.
 20. Anarticle according to claim 19, wherein the proportion of storage layerforming the receiving space decreases in a direction away from said areaof the article.
 21. An article according to claim 1, wherein the webforming the storage layer is divided along more than one dividing curveextending in the longitudinal direction of the web.